Augmented collisional ionization via excited states in XUV cluster interactions

The impact of atomic excited states is investigated via a detailed model of laser-cluster interactions, which is applied to rare gas clusters in intense femtosecond pulses in the extreme ultraviolet (XUV). This demonstrates the potential for a two-step ionization process in laser-cluster interactions, with the resulting intermediate excited states allowing for the creation of high charge states and the rapid dissemination of laser pulse energy. The consequences of this excitation mechanism are demonstrated through simulations of recent experiments in argon clusters interacting with XUV radiation, in which this two-step process is shown to play a primary role; this is consistent with our hypothesis that XUV-cluster interactions provide a unique window into the role of excited atomic states due to the relative lack of photoionization and laser field-driven phenomena. Our analysis suggests that atomic excited states may play an important role in interactions of intense radiation with materials in a variety of wavelength regimes, including potential implications for proposed studies of single molecule imaging with intense X-rays.Comment: 4 pages, 2 figure

Subsídios técnicos para a produção e comercialização de sementes certificadas do coqueiro.

Discute produção de sementes de coqueiro, auxiliando o Ministério da Agricultura e Abastecimento no processo de certificação, auxiliar os produtores de coco na aquisição de sementes de coco, auxilia no controle do comércio clandestino de sementes de coqueiro além de outras assuntos.bitstream/item/46722/1/CPATC-DOCUMENTOS-10-SUBSIDIOS-TECNICOS-PARA-A-PRODUCAO-E-COMERCIALIZACAO-DE-SEMENTES-CERTIFICADAS.pd

Stochastic Pulse Regulation in Bacterial Stress Response

Gene regulatory circuits can use dynamic, and even stochastic, strategies to respond to environmental conditions. We examined activation of the general stress response mediated by the alternative sigma factor, σ^B, in individual Bacillus subtilis cells. We observed that energy stress activates σ^B in discrete stochastic pulses, with increasing levels of stress leading to higher pulse frequencies. By perturbing and rewiring the endogenous system, we found that this behavior results from three key features of the σ^B circuit: an ultrasensitive phosphorylation switch; stochasticity (“noise”), which activates that switch; and a mixed (positive and negative) transcriptional feedback, which can both amplify a pulse and switch it off. Together, these results show how prokaryotes encode signals using stochastic pulse frequency modulation through a compact regulatory architecture

Resposta de cultivares de tomateiro para processamento industrial a fertirrigacao por gotejamento subterraneo.

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Acúmulo de carbono no solo no sistema plantio direto de milho no Amazonas.

No Estado do Amazonas poucos estudos foram realizados sobre a utilização do sistema plantio direto. Assim, o objetivo foi avaliar o efeito do sistema plantio direto sobre o acúmulo de carbono orgânico total do solo ao longo do tempo na cultura do milho